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93dc6107 |
| 16-Mar-2012 |
Jason Baron <jbaron@redhat.com> |
Don't limit non-nested epoll paths
Commit 28d82dc1c4ed ("epoll: limit paths") that I did to limit the number of possible wakeup paths in epoll is causing a few applications to longer work (dovecot f
Don't limit non-nested epoll paths
Commit 28d82dc1c4ed ("epoll: limit paths") that I did to limit the number of possible wakeup paths in epoll is causing a few applications to longer work (dovecot for one).
The original patch is really about limiting the amount of epoll nesting (since epoll fds can be attached to other fds). Thus, we probably can allow an unlimited number of paths of depth 1. My current patch limits it at 1000. And enforce the limits on paths that have a greater depth.
This is captured in: https://bugzilla.redhat.com/show_bug.cgi?id=681578
Signed-off-by: Jason Baron <jbaron@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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971316f0 |
| 24-Feb-2012 |
Oleg Nesterov <oleg@redhat.com> |
epoll: ep_unregister_pollwait() can use the freed pwq->whead
signalfd_cleanup() ensures that ->signalfd_wqh is not used, but this is not enough. eppoll_entry->whead still points to the memory we are
epoll: ep_unregister_pollwait() can use the freed pwq->whead
signalfd_cleanup() ensures that ->signalfd_wqh is not used, but this is not enough. eppoll_entry->whead still points to the memory we are going to free, ep_unregister_pollwait()->remove_wait_queue() is obviously unsafe.
Change ep_poll_callback(POLLFREE) to set eppoll_entry->whead = NULL, change ep_unregister_pollwait() to check pwq->whead != NULL under rcu_read_lock() before remove_wait_queue(). We add the new helper, ep_remove_wait_queue(), for this.
This works because sighand_cachep is SLAB_DESTROY_BY_RCU and because ->signalfd_wqh is initialized in sighand_ctor(), not in copy_sighand. ep_unregister_pollwait()->remove_wait_queue() can play with already freed and potentially reused ->sighand, but this is fine. This memory must have the valid ->signalfd_wqh until rcu_read_unlock().
Reported-by: Maxime Bizon <mbizon@freebox.fr> Cc: <stable@kernel.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d80e731e |
| 24-Feb-2012 |
Oleg Nesterov <oleg@redhat.com> |
epoll: introduce POLLFREE to flush ->signalfd_wqh before kfree()
This patch is intentionally incomplete to simplify the review. It ignores ep_unregister_pollwait() which plays with the same wqh. See
epoll: introduce POLLFREE to flush ->signalfd_wqh before kfree()
This patch is intentionally incomplete to simplify the review. It ignores ep_unregister_pollwait() which plays with the same wqh. See the next change.
epoll assumes that the EPOLL_CTL_ADD'ed file controls everything f_op->poll() needs. In particular it assumes that the wait queue can't go away until eventpoll_release(). This is not true in case of signalfd, the task which does EPOLL_CTL_ADD uses its ->sighand which is not connected to the file.
This patch adds the special event, POLLFREE, currently only for epoll. It expects that init_poll_funcptr()'ed hook should do the necessary cleanup. Perhaps it should be defined as EPOLLFREE in eventpoll.
__cleanup_sighand() is changed to do wake_up_poll(POLLFREE) if ->signalfd_wqh is not empty, we add the new signalfd_cleanup() helper.
ep_poll_callback(POLLFREE) simply does list_del_init(task_list). This make this poll entry inconsistent, but we don't care. If you share epoll fd which contains our sigfd with another process you should blame yourself. signalfd is "really special". I simply do not know how we can define the "right" semantics if it used with epoll.
The main problem is, epoll calls signalfd_poll() once to establish the connection with the wait queue, after that signalfd_poll(NULL) returns the different/inconsistent results depending on who does EPOLL_CTL_MOD/signalfd_read/etc. IOW: apart from sigmask, signalfd has nothing to do with the file, it works with the current thread.
In short: this patch is the hack which tries to fix the symptoms. It also assumes that nobody can take tasklist_lock under epoll locks, this seems to be true.
Note:
- we do not have wake_up_all_poll() but wake_up_poll() is fine, poll/epoll doesn't use WQ_FLAG_EXCLUSIVE.
- signalfd_cleanup() uses POLLHUP along with POLLFREE, we need a couple of simple changes in eventpoll.c to make sure it can't be "lost".
Reported-by: Maxime Bizon <mbizon@freebox.fr> Cc: <stable@kernel.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
28d82dc1 |
| 13-Jan-2012 |
Jason Baron <jbaron@redhat.com> |
epoll: limit paths
The current epoll code can be tickled to run basically indefinitely in both loop detection path check (on ep_insert()), and in the wakeup paths. The programs that tickle this beha
epoll: limit paths
The current epoll code can be tickled to run basically indefinitely in both loop detection path check (on ep_insert()), and in the wakeup paths. The programs that tickle this behavior set up deeply linked networks of epoll file descriptors that cause the epoll algorithms to traverse them indefinitely. A couple of these sample programs have been previously posted in this thread: https://lkml.org/lkml/2011/2/25/297.
To fix the loop detection path check algorithms, I simply keep track of the epoll nodes that have been already visited. Thus, the loop detection becomes proportional to the number of epoll file descriptor and links. This dramatically decreases the run-time of the loop check algorithm. In one diabolical case I tried it reduced the run-time from 15 mintues (all in kernel time) to .3 seconds.
Fixing the wakeup paths could be done at wakeup time in a similar manner by keeping track of nodes that have already been visited, but the complexity is harder, since there can be multiple wakeups on different cpus...Thus, I've opted to limit the number of possible wakeup paths when the paths are created.
This is accomplished, by noting that the end file descriptor points that are found during the loop detection pass (from the newly added link), are actually the sources for wakeup events. I keep a list of these file descriptors and limit the number and length of these paths that emanate from these 'source file descriptors'. In the current implemetation I allow 1000 paths of length 1, 500 of length 2, 100 of length 3, 50 of length 4 and 10 of length 5. Note that it is sufficient to check the 'source file descriptors' reachable from the newly added link, since no other 'source file descriptors' will have newly added links. This allows us to check only the wakeup paths that may have gotten too long, and not re-check all possible wakeup paths on the system.
In terms of the path limit selection, I think its first worth noting that the most common case for epoll, is probably the model where you have 1 epoll file descriptor that is monitoring n number of 'source file descriptors'. In this case, each 'source file descriptor' has a 1 path of length 1. Thus, I believe that the limits I'm proposing are quite reasonable and in fact may be too generous. Thus, I'm hoping that the proposed limits will not prevent any workloads that currently work to fail.
In terms of locking, I have extended the use of the 'epmutex' to all epoll_ctl add and remove operations. Currently its only used in a subset of the add paths. I need to hold the epmutex, so that we can correctly traverse a coherent graph, to check the number of paths. I believe that this additional locking is probably ok, since its in the setup/teardown paths, and doesn't affect the running paths, but it certainly is going to add some extra overhead. Also, worth noting is that the epmuex was recently added to the ep_ctl add operations in the initial path loop detection code using the argument that it was not on a critical path.
Another thing to note here, is the length of epoll chains that is allowed. Currently, eventpoll.c defines:
/* Maximum number of nesting allowed inside epoll sets */ #define EP_MAX_NESTS 4
This basically means that I am limited to a graph depth of 5 (EP_MAX_NESTS + 1). However, this limit is currently only enforced during the loop check detection code, and only when the epoll file descriptors are added in a certain order. Thus, this limit is currently easily bypassed. The newly added check for wakeup paths, stricly limits the wakeup paths to a length of 5, regardless of the order in which ep's are linked together. Thus, a side-effect of the new code is a more consistent enforcement of the graph depth.
Thus far, I've tested this, using the sample programs previously mentioned, which now either return quickly or return -EINVAL. I've also testing using the piptest.c epoll tester, which showed no difference in performance. I've also created a number of different epoll networks and tested that they behave as expectded.
I believe this solves the original diabolical test cases, while still preserving the sane epoll nesting.
Signed-off-by: Jason Baron <jbaron@redhat.com> Cc: Nelson Elhage <nelhage@ksplice.com> Cc: Davide Libenzi <davidel@xmailserver.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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d8805e63 |
| 01-Nov-2011 |
Nelson Elhage <nelhage@nelhage.com> |
epoll: fix spurious lockdep warnings
epoll can acquire recursively acquire ep->mtx on multiple "struct eventpoll"s at once in the case where one epoll fd is monitoring another epoll fd. This is per
epoll: fix spurious lockdep warnings
epoll can acquire recursively acquire ep->mtx on multiple "struct eventpoll"s at once in the case where one epoll fd is monitoring another epoll fd. This is perfectly OK, since we're careful about the lock ordering, but it causes spurious lockdep warnings. Annotate the recursion using mutex_lock_nested, and add a comment explaining the nesting rules for good measure.
Recent versions of systemd are triggering this, and it can also be demonstrated with the following trivial test program:
--------------------8<--------------------
int main(void) { int e1, e2; struct epoll_event evt = { .events = EPOLLIN };
e1 = epoll_create1(0); e2 = epoll_create1(0); epoll_ctl(e1, EPOLL_CTL_ADD, e2, &evt); return 0; } --------------------8<--------------------
Reported-by: Paul Bolle <pebolle@tiscali.nl> Tested-by: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Nelson Elhage <nelhage@nelhage.com> Acked-by: Jason Baron <jbaron@redhat.com> Cc: Dave Jones <davej@redhat.com> Cc: Davide Libenzi <davidel@xmailserver.org> Cc: <stable@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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60063497 |
| 26-Jul-2011 |
Arun Sharma <asharma@fb.com> |
atomic: use <linux/atomic.h>
This allows us to move duplicated code in <asm/atomic.h> (atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: Arun Sharma <asharma@fb.com> Reviewed-by: Er
atomic: use <linux/atomic.h>
This allows us to move duplicated code in <asm/atomic.h> (atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: Arun Sharma <asharma@fb.com> Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Acked-by: Mike Frysinger <vapier@gentoo.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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10bd2473 |
| 24-Jul-2011 |
Paul Bolle <pebolle@tiscali.nl> |
eventpoll: fix comment typo 'evenpoll'
Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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25985edc |
| 31-Mar-2011 |
Lucas De Marchi <lucas.demarchi@profusion.mobi> |
Fix common misspellings
Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
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f4d93ad7 |
| 22-Mar-2011 |
Shawn Bohrer <shawn.bohrer@gmail.com> |
epoll: fix compiler warning and optimize the non-blocking path
Add a comment to ep_poll(), rename labels a bit clearly, fix a warning of unused variable from gcc and optimize the non-blocking path a
epoll: fix compiler warning and optimize the non-blocking path
Add a comment to ep_poll(), rename labels a bit clearly, fix a warning of unused variable from gcc and optimize the non-blocking path a little.
Hinted-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
hannes@cmpxchg.org:
: The non-blocking ep_poll path optimization introduced skipping over the : return value setup. : : Initialize it properly, my userspace gets upset by epoll_wait() returning : random things. : : In addition, remove the reinitialization at the fetch_events label, the : return value is garuanteed to be zero when execution reaches there.
[hannes@cmpxchg.org: fix initialization] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Shawn Bohrer <shawn.bohrer@gmail.com> Acked-by: Davide Libenzi <davidel@xmailserver.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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3fb0e584 |
| 22-Mar-2011 |
Davide Libenzi <davidel@xmailserver.org> |
epoll: move ready event check into proper inline
Move the event readiness check into a proper inline, and use it uniformly inside ep_poll() code. Events in the ->ovflist are no less ready than the
epoll: move ready event check into proper inline
Move the event readiness check into a proper inline, and use it uniformly inside ep_poll() code. Events in the ->ovflist are no less ready than the ones in ->rdllist.
Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Cc: Shawn Bohrer <shawn.bohrer@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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22bacca4 |
| 25-Feb-2011 |
Davide Libenzi <davidel@xmailserver.org> |
epoll: prevent creating circular epoll structures
In several places, an epoll fd can call another file's ->f_op->poll() method with ep->mtx held. This is in general unsafe, because that other file
epoll: prevent creating circular epoll structures
In several places, an epoll fd can call another file's ->f_op->poll() method with ep->mtx held. This is in general unsafe, because that other file could itself be an epoll fd that contains the original epoll fd.
The code defends against this possibility in its own ->poll() method using ep_call_nested, but there are several other unsafe calls to ->poll elsewhere that can be made to deadlock. For example, the following simple program causes the call in ep_insert recursively call the original fd's ->poll, leading to deadlock:
#include <unistd.h> #include <sys/epoll.h>
int main(void) { int e1, e2, p[2]; struct epoll_event evt = { .events = EPOLLIN };
e1 = epoll_create(1); e2 = epoll_create(2); pipe(p);
epoll_ctl(e2, EPOLL_CTL_ADD, e1, &evt); epoll_ctl(e1, EPOLL_CTL_ADD, p[0], &evt); write(p[1], p, sizeof p); epoll_ctl(e1, EPOLL_CTL_ADD, e2, &evt);
return 0; }
On insertion, check whether the inserted file is itself a struct epoll, and if so, do a recursive walk to detect whether inserting this file would create a loop of epoll structures, which could lead to deadlock.
[nelhage@ksplice.com: Use epmutex to serialize concurrent inserts] Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Signed-off-by: Nelson Elhage <nelhage@ksplice.com> Reported-by: Nelson Elhage <nelhage@ksplice.com> Tested-by: Nelson Elhage <nelhage@ksplice.com> Cc: <stable@kernel.org> [2.6.34+, possibly earlier] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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bf6a41db |
| 30-Jan-2011 |
Daniel Baluta <daniel.baluta@gmail.com> |
fs/eventpoll.c: fix spelling
eventpoll.c has wonderful comments but some annoying typos sneaked in: * toepoll_ctl -> to epoll_ctl * rapresent -> represents * sructure -> structure * machanism ->
fs/eventpoll.c: fix spelling
eventpoll.c has wonderful comments but some annoying typos sneaked in: * toepoll_ctl -> to epoll_ctl * rapresent -> represents * sructure -> structure * machanism -> mechanism * trasfering -> transferring
Signed-off-by: Daniel Baluta <daniel.baluta@gmail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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0781b909 |
| 01-Feb-2011 |
Eric Dumazet <eric.dumazet@gmail.com> |
epoll: epoll_wait() should not use timespec_add_ns()
commit 95aac7b1cd224f ("epoll: make epoll_wait() use the hrtimer range feature") added a performance regression because it uses timespec_add_ns()
epoll: epoll_wait() should not use timespec_add_ns()
commit 95aac7b1cd224f ("epoll: make epoll_wait() use the hrtimer range feature") added a performance regression because it uses timespec_add_ns() with potential very large 'ns' values.
[akpm@linux-foundation.org: s/epoll_set_mstimeout/ep_set_mstimeout/, per Davide] Reported-by: Simon Kirby <sim@hostway.ca> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Shawn Bohrer <shawn.bohrer@gmail.com> Acked-by: Davide Libenzi <davidel@xmailserver.org> Cc: <stable@kernel.org> [2.6.37.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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52bd19f7 |
| 13-Jan-2011 |
Robin Holt <holt@sgi.com> |
epoll: convert max_user_watches to long
On a 16TB machine, max_user_watches has an integer overflow. Convert it to use a long and handle the associated fallout.
Signed-off-by: Robin Holt <holt@sgi
epoll: convert max_user_watches to long
On a 16TB machine, max_user_watches has an integer overflow. Convert it to use a long and handle the associated fallout.
Signed-off-by: Robin Holt <holt@sgi.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Acked-by: Davide Libenzi <davidel@xmailserver.org> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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95aac7b1 |
| 27-Oct-2010 |
Shawn Bohrer <shawn.bohrer@gmail.com> |
epoll: make epoll_wait() use the hrtimer range feature
This make epoll use hrtimers for the timeout value which prevents epoll_wait() from timing out up to a millisecond early.
This mirrors the beh
epoll: make epoll_wait() use the hrtimer range feature
This make epoll use hrtimers for the timeout value which prevents epoll_wait() from timing out up to a millisecond early.
This mirrors the behavior of select() and poll().
Signed-off-by: Shawn Bohrer <shawn.bohrer@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Acked-by: Davide Libenzi <davidel@xmailserver.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
6038f373 |
| 15-Aug-2010 |
Arnd Bergmann <arnd@arndb.de> |
llseek: automatically add .llseek fop
All file_operations should get a .llseek operation so we can make nonseekable_open the default for future file operations without a .llseek pointer.
The three
llseek: automatically add .llseek fop
All file_operations should get a .llseek operation so we can make nonseekable_open the default for future file operations without a .llseek pointer.
The three cases that we can automatically detect are no_llseek, seq_lseek and default_llseek. For cases where we can we can automatically prove that the file offset is always ignored, we use noop_llseek, which maintains the current behavior of not returning an error from a seek.
New drivers should normally not use noop_llseek but instead use no_llseek and call nonseekable_open at open time. Existing drivers can be converted to do the same when the maintainer knows for certain that no user code relies on calling seek on the device file.
The generated code is often incorrectly indented and right now contains comments that clarify for each added line why a specific variant was chosen. In the version that gets submitted upstream, the comments will be gone and I will manually fix the indentation, because there does not seem to be a way to do that using coccinelle.
Some amount of new code is currently sitting in linux-next that should get the same modifications, which I will do at the end of the merge window.
Many thanks to Julia Lawall for helping me learn to write a semantic patch that does all this.
===== begin semantic patch ===== // This adds an llseek= method to all file operations, // as a preparation for making no_llseek the default. // // The rules are // - use no_llseek explicitly if we do nonseekable_open // - use seq_lseek for sequential files // - use default_llseek if we know we access f_pos // - use noop_llseek if we know we don't access f_pos, // but we still want to allow users to call lseek // @ open1 exists @ identifier nested_open; @@ nested_open(...) { <+... nonseekable_open(...) ...+> }
@ open exists@ identifier open_f; identifier i, f; identifier open1.nested_open; @@ int open_f(struct inode *i, struct file *f) { <+... ( nonseekable_open(...) | nested_open(...) ) ...+> }
@ read disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> }
@ read_no_fpos disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { ... when != off }
@ write @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> }
@ write_no_fpos @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { ... when != off }
@ fops0 @ identifier fops; @@ struct file_operations fops = { ... };
@ has_llseek depends on fops0 @ identifier fops0.fops; identifier llseek_f; @@ struct file_operations fops = { ... .llseek = llseek_f, ... };
@ has_read depends on fops0 @ identifier fops0.fops; identifier read_f; @@ struct file_operations fops = { ... .read = read_f, ... };
@ has_write depends on fops0 @ identifier fops0.fops; identifier write_f; @@ struct file_operations fops = { ... .write = write_f, ... };
@ has_open depends on fops0 @ identifier fops0.fops; identifier open_f; @@ struct file_operations fops = { ... .open = open_f, ... };
// use no_llseek if we call nonseekable_open //////////////////////////////////////////// @ nonseekable1 depends on !has_llseek && has_open @ identifier fops0.fops; identifier nso ~= "nonseekable_open"; @@ struct file_operations fops = { ... .open = nso, ... +.llseek = no_llseek, /* nonseekable */ };
@ nonseekable2 depends on !has_llseek @ identifier fops0.fops; identifier open.open_f; @@ struct file_operations fops = { ... .open = open_f, ... +.llseek = no_llseek, /* open uses nonseekable */ };
// use seq_lseek for sequential files ///////////////////////////////////// @ seq depends on !has_llseek @ identifier fops0.fops; identifier sr ~= "seq_read"; @@ struct file_operations fops = { ... .read = sr, ... +.llseek = seq_lseek, /* we have seq_read */ };
// use default_llseek if there is a readdir /////////////////////////////////////////// @ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier readdir_e; @@ // any other fop is used that changes pos struct file_operations fops = { ... .readdir = readdir_e, ... +.llseek = default_llseek, /* readdir is present */ };
// use default_llseek if at least one of read/write touches f_pos ///////////////////////////////////////////////////////////////// @ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read.read_f; @@ // read fops use offset struct file_operations fops = { ... .read = read_f, ... +.llseek = default_llseek, /* read accesses f_pos */ };
@ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, ... + .llseek = default_llseek, /* write accesses f_pos */ };
// Use noop_llseek if neither read nor write accesses f_pos ///////////////////////////////////////////////////////////
@ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; identifier write_no_fpos.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, .read = read_f, ... +.llseek = noop_llseek, /* read and write both use no f_pos */ };
@ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write_no_fpos.write_f; @@ struct file_operations fops = { ... .write = write_f, ... +.llseek = noop_llseek, /* write uses no f_pos */ };
@ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; @@ struct file_operations fops = { ... .read = read_f, ... +.llseek = noop_llseek, /* read uses no f_pos */ };
@ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; @@ struct file_operations fops = { ... +.llseek = noop_llseek, /* no read or write fn */ }; ===== End semantic patch =====
Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Julia Lawall <julia@diku.dk> Cc: Christoph Hellwig <hch@infradead.org>
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a93d2f17 |
| 07-May-2010 |
Changli Gao <xiaosuo@gmail.com> |
sched, wait: Use wrapper functions
epoll should not touch flags in wait_queue_t. This patch introduces a new function __add_wait_queue_exclusive(), for the users, who use wait queue as a LIFO queue.
sched, wait: Use wrapper functions
epoll should not touch flags in wait_queue_t. This patch introduces a new function __add_wait_queue_exclusive(), for the users, who use wait queue as a LIFO queue.
__add_wait_queue_tail_exclusive() is introduced too instead of add_wait_queue_exclusive_locked(). remove_wait_queue_locked() is removed, as it is a duplicate of __remove_wait_queue(), disliked by users, and with less users.
Signed-off-by: Changli Gao <xiaosuo@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Paul Menage <menage@google.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Davide Libenzi <davidel@xmailserver.org> Cc: <containers@lists.linux-foundation.org> LKML-Reference: <1273214006-2979-1-git-send-email-xiaosuo@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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#
628ff7c1 |
| 18-Dec-2009 |
Roland Dreier <rdreier@cisco.com> |
anonfd: Allow making anon files read-only
It seems a couple places such as arch/ia64/kernel/perfmon.c and drivers/infiniband/core/uverbs_main.c could use anon_inode_getfile() instead of a private ps
anonfd: Allow making anon files read-only
It seems a couple places such as arch/ia64/kernel/perfmon.c and drivers/infiniband/core/uverbs_main.c could use anon_inode_getfile() instead of a private pseudo-fs + alloc_file(), if only there were a way to get a read-only file. So provide this by having anon_inode_getfile() create a read-only file if we pass O_RDONLY in flags.
Signed-off-by: Roland Dreier <rolandd@cisco.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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#
6d456111 |
| 16-Nov-2009 |
Eric W. Biederman <ebiederm@xmission.com> |
sysctl: Drop & in front of every proc_handler.
For consistency drop & in front of every proc_handler. Explicity taking the address is unnecessary and it prevents optimizations like stubbing the pro
sysctl: Drop & in front of every proc_handler.
For consistency drop & in front of every proc_handler. Explicity taking the address is unnecessary and it prevents optimizations like stubbing the proc_handlers to NULL.
Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Joe Perches <joe@perches.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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#
ab09203e |
| 05-Nov-2009 |
Eric W. Biederman <ebiederm@xmission.com> |
sysctl fs: Remove dead binary sysctl support
Now that sys_sysctl is a generic wrapper around /proc/sys .ctl_name and .strategy members of sysctl tables are dead code. Remove them.
Cc: Jan Harkes
sysctl fs: Remove dead binary sysctl support
Now that sys_sysctl is a generic wrapper around /proc/sys .ctl_name and .strategy members of sysctl tables are dead code. Remove them.
Cc: Jan Harkes <jaharkes@cs.cmu.edu> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
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#
3fe4a975 |
| 17-Jun-2009 |
Davide Libenzi <davidel@xmailserver.org> |
epoll: fix nested calls support
This fixes a regression in 2.6.30.
I unfortunately accepted a patch time ago, to drop the "current" usage from possible IRQ context, w/out proper thought over it. T
epoll: fix nested calls support
This fixes a regression in 2.6.30.
I unfortunately accepted a patch time ago, to drop the "current" usage from possible IRQ context, w/out proper thought over it. The patch switched to using the CPU id by bounding the nested call callback with a get_cpu()/put_cpu().
Unfortunately the ep_call_nested() function can be called with a callback that grabs sleepy locks (from own f_op->poll()), that results in epic fails. The following patch uses the proper "context" depending on the path where it is called, and on the kind of callback.
This has been reported by Stefan Richter, that has also verified the patch is his previously failing environment.
Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Reported-by: Stefan Richter <stefanr@s5r6.in-berlin.de> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
bfe3891a |
| 12-May-2009 |
Davide Libenzi <davidel@xmailserver.org> |
epoll: fix size check in epoll_create()
Fix a size check WRT the manual pages. This was inadvertently broken by commit 9fe5ad9c8cef9ad5873d8ee55d1cf00d9b607df0 ("flag parameters add-on: remove epol
epoll: fix size check in epoll_create()
Fix a size check WRT the manual pages. This was inadvertently broken by commit 9fe5ad9c8cef9ad5873d8ee55d1cf00d9b607df0 ("flag parameters add-on: remove epoll_create size param").
Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Cc: <Hiroyuki.Mach@gmail.com> Cc: rohit verma <rohit.170309@gmail.com> Cc: Ulrich Drepper <drepper@redhat.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
2dfa4eea |
| 31-Mar-2009 |
Davide Libenzi <davidel@xmailserver.org> |
epoll keyed wakeups: teach epoll about hints coming with the wakeup key
Use the events hint now sent by some devices, to avoid unnecessary wakeups for events that are of no interest for the caller.
epoll keyed wakeups: teach epoll about hints coming with the wakeup key
Use the events hint now sent by some devices, to avoid unnecessary wakeups for events that are of no interest for the caller. This code handles both devices that are sending keyed events, and the ones that are not (and event the ones that sometimes send events, and sometimes don't).
[akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Ingo Molnar <mingo@elte.hu> Cc: David Miller <davem@davemloft.net> Cc: William Lee Irwin III <wli@movementarian.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
4f0989db |
| 31-Mar-2009 |
Tony Battersby <tonyb@cybernetics.com> |
epoll: use real type instead of void *
eventpoll.c uses void * in one place for no obvious reason; change it to use the real type instead.
Signed-off-by: Tony Battersby <tonyb@cybernetics.com> Acke
epoll: use real type instead of void *
eventpoll.c uses void * in one place for no obvious reason; change it to use the real type instead.
Signed-off-by: Tony Battersby <tonyb@cybernetics.com> Acked-by: Davide Libenzi <davidel@xmailserver.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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#
e057e15f |
| 31-Mar-2009 |
Tony Battersby <tonyb@cybernetics.com> |
epoll: clean up ep_modify
ep_modify() doesn't need to set event.data from within the ep->lock spinlock as the comment suggests. The only place event.data is used is ep_send_events_proc(), and this
epoll: clean up ep_modify
ep_modify() doesn't need to set event.data from within the ep->lock spinlock as the comment suggests. The only place event.data is used is ep_send_events_proc(), and this is protected by ep->mtx instead of ep->lock. Also update the comment for mutex_lock() at the top of ep_scan_ready_list(), which mentions epoll_ctl(EPOLL_CTL_DEL) but not epoll_ctl(EPOLL_CTL_MOD).
ep_modify() can also use spin_lock_irq() instead of spin_lock_irqsave().
Signed-off-by: Tony Battersby <tonyb@cybernetics.com> Acked-by: Davide Libenzi <davidel@xmailserver.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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